Magnetic display device and method of making same



p 1941- J. H. SCHARF 2,254,498 MAGNETIC DISPLAY DEVICE AND METHOD OF MAKING SQM E Filed 001:. 5, 1938 2 Sheets-Sheet l p 1941- J. H. SCHARF 2,254,498

MAGNETIC DISPLAY DEVICE AND METHOD OF MAKING SAME Filed Oct. 5 1938 2 Sheets-Sheet 2 "WW 7 A Patented Sept..2, 1941 MAGNETIC DISPLAY DEVICE AND METHOD 4 OF MAKING SAME John H. Scharf, Omaha, Nebn, assignor, by man assignments, to Quixet, Inc., a corporation of Application October 5, 1938, Serial No. 233,426

9 Claims.

This application is a. continuation in part of my pending application, Serial Number 101,847, filed September 21, 1936 for Magnetic display signs. 1

This invention relates generally to magnetic display devices and method of making same and which display devices or signs are adapted for advertising purposes. The invention has particular reference to that class of. signs or devices having interchangeable elements as letters, numerals, symbols, illustrations, insignia or the like and wherein the said indicia are provided with magnets for cooperation with a magnetically responsive display board or panel therefor.

I am "aware of the fact that .the prior art comprising the class of inventions to which my invention is related includes magnetic boards of heavy and expensive construction having a body composed of many adjacently mounted magnets presenting surfaces on which various elements or para-magnetic objects of metal or other material with metallic base may be supported, but in all of such display devices there are objectionable limitations and disadvantages in the excessive weight and cost of such magnet carrying boards and the display elements to be applied thereon and which elements must be either of solid metal or other material provided with a paramagnetic backing. An objection common to the solid metal character or display element having integral or attached magnetic feet is that its weight makes it very difficult to prevent creeping and retainment on the display panel unless provided with many comparatively large and costly magnetic feet, and alsothat the eifect of such display element as being an intebody of the indicium that the maximumforce v of attraction is practically within the central portion of the section of the body in which it is located, and that the longitudinal axis of the magnetic circuitor field is as much as practically possible closely parallel to the longitudinalcenter line of that portion of the body, and so that such magnetic field extends beyond the opposite sides of such section of the indicium, and further, to so mount the several magnets, as far as practically possible, at balanced. points relatively to the center of gravity of the indicium and with the adjacently disposed poles of the different magnets of opposite polarity.

Still. another object of my invention resides in the provision of cast or molded indicia of thermo-pl-astic material each consisting of a very thin-walled, shell-like, hollow body having certain struts formed integrally with and disposed transversely to spaced opposite side walls,

and which struts constitute end reenforcing walls for the magnet cavities for resisting deformation or cracking of such opposite side walls upon forceful insertion of the magnets. Such lightweight shell-like indicia are not only low in cost gral part of the panel is destroyed by the visibiltty of the extended feet'thereof.

It is therefore an object of my invention to 40 increase the efliciency and reduce the cost of magnetically-applied indicia and to adapt same to a wide field of uses and adaptations.

Another object of my invention is to provide a display device including a display board or panel of para-magnetic material such as iron or steel, painted or illustrated, if so desired, in respectively any desirable color or illustration to constitute a supporting back-ground for display elements or instrumentalities of non-magnetic, light-weight and inexpensive thermoplastic material of a cellulose acetate base, or other suitable base, representing different, various or desired indicia and which elements are provided of manufacture but their light weight tends to overcome creeping on vertical surfaces often caused by'vibrations transmitted to buildings by railroads or other vehicles. Other struts formed integrally with the side walls may be provided with small holes into which pins may be inserted to thereby adapt such indicia to pin securance upon a wooden or paper back-ground in which adaptation the magnets may be dispensed with.

Other and further objects and advantages of the invention will become apparent from the following detailed description thereof, reference being bad to the accompanying drawings showing preferred embodiments of my invention:

Fig. 1 is a. fragmentary perspective view of a sign or display device embodying certain features of the present invention;

Fig. 2 is a transverse section taken through with a small magnet or magnets secured within the same on line 2-2 of Fig. 1;

play element having the magnet mounted there- Fig. 8 is a rear elevation of.a display element, showing a slight modification in the construction thereof and of the magnets mounted therein;

Fig. 9 is a transverse section taken through a display element showing a modification of the same and of a magnet mounted therein;

Fig. 10 is a cross-section taken on line Ill-40 of Fig. 8 showing supplemental friction producing means;

Fig. 11 is an enlarged rear view of the letters N, W and made in accordance with preferred embodiments of my invention and before insertion of magnets or pins;

Fig. 12 is a view similar to Fig. 11 but showing the letters N, W and O equipped with magnets;

Fig. 13 is a cross-section taken on line |2-|2 of Fig. 11 showing a pair of the small side wall ribs for retaining the magnet;

Fig. 14 is a cross-section taken on line |4|4 of Fig. 12 showing the magnet in place;

Fig. 15 is a cross-section taken on line |-|5 of Fig. 12 showing the magnet and retaining ribs; Fig. 16 is a cross-section taken on line |6|6 of Fig; 12 showing one of the pins when such letter is adapted for retainment on a wooden or paper back-ground, and

Fig. 17 is a cross-section taken on line I 'I-ll of Fig. 12' showing the magnet in longitudinal section. Referring now to the drawings, and particularly to Figs. 1 to inclusive, 20 dwignates a display panel or board which may be of any suitable para-magnetic material, in whole or in part, so as to provide a display board possessing magnetic properties. Covering the face of the board is a ground sheet 2| which may consist of a light coat of paint or colored or illustrated paper or other suitable material capable of being applied, attached or held in place on the board and one which will not interfere with the function of the magnetic properties of the board or body portion 20. A marginal head or rail 22 may be disposed about the marginal portion of the board 20 against the sheet 2|, if desired and this rail or head 22 may be of any suitable substance and may be secured in place in any well known manner as by screws to retain the interchangeable sheet 2|, or it may, as shown, be constructed of a magnetizable material capable of being held by magnetic attraction in position on'the board 20. Thus, the rails 22 may be fixed, detachable or removable and capable of being interchanged with other rails or beads of similar general characteristics to produce difierent effects at the face 0 the sign.

The display face of the board 20 is adapted to i hold one or more display elements 22. These display elements 23 may be in the form of letters as shown in Fi 1, or may represent numerals, objects, fanciful configurations, pictorial illustraindicium is preferably constructed of a body portion molded, cast or formed of non-magnetic thermo-plastic material such as plastic wood, Bakelite, rubber or compressed fiber and is provided with one or more recesses in its rear face for the reception therein of one or more magnets 24.

The recesses in the rear face of the display element 22 are preferably disposed lengthwise therein with respect to the particular portions of the section of the element in which they are disposed, and the magnets 24, shown in Fig. 4, are preferably of rectangular elongated bar form and may be provided intermediately with a relatively deep notch 25 or elongated recess 22 as shown in Fig. 17, dividing the bar into opposite end poles of opposite polarity and forming a generally U type magnet. The magnet 24 is made of magnetizable or magnetic material and is adapted to cooperate with the para-magnetic board 22 for holding the display elements 22 at any desired position upon the face of the sign.

These magnets 24 may be secured in the element during molding or casting thereof or may be preferably secured in position in the recesses of the display elements by friction or by a filler of plastic or cementitious material 22 capable of holding the magnets 24 within the display element, and the magnet 24 and the cementitious material 26 are positioned or ground or otherwise finished ofi flush with the rear face of the display element 50 that the latter may lie fiat against the face of the board 22 or its cover 2t and the magnet 24 be exposed thereagainst. The interpositioning of the ground sheet 2| does not effect the magnetic attraction between the board body 20 and one or more magnets 24 of the elements employed, so that the ground sheet 2| may be of any suitable color and may carry any suitable configurations or illustrations such as scenic or pictorial representations of various kind which will blend with or serve the purpose of the various display elements when the latter are positioned on the board and with respect to the representations on the ground sheet.

As shown in Fig. 8, the display element 21, which represents the letter 0, may be of circular or other suitable curved configuration and the recesses for the magnets may be correspondingly curved so as to extend lengthwise of or in parallel relation to the particular portions of the display element in which the magnets are disposed. In this instance the magnets 28 are correspondingly curved throughout their length so as to conform to the curved recesses.

As shown in Fig. 9, the magnet 29 may be cast or molded in the rear face of the display element 30 and additionally secured by a dovetail joint with the side portions of the display element 30.

As shown in Figs. 8-and 10, a small body of a friction producing element 2|, such as soft rubber, latex, or any other semi-plastic adhesive material, may be placed or secured in the cavity 22 the indicia supported thereon.

In Fig. 7, the displayed element 24 is given the configuration of the letter I, in Fig. 3 the display element 23 is in the form of the letter F, and in Fig. 8 the display element is in the form of the letter O.

It is evident, that the display elements or indicia may be different shapes, sizes and configurations to cooperate with the sign board 20, and of course the display elements may be of various colors and lightweight materials, and may be transparent, opaque or the like, in order to effectively setout the desired display.

The display elements may be molded, cast or otherwise formed as by means of a die, and the recess or recesses in the rear face of the element may be formed in the initial formation of the element. The magnet 24, or 28, may be given any other suitable configuration than as shown for accommodating it to the recess which is provided in the rear face of the display element. As the exposed surfaces of the magnet 24 are disposed substantially flush with the rear face of the display element, the latter fits snugly against the back-ground sheet 2| and imparts to the eye the appearance of being molded or cast as an integral-structure with the background or the display board. Of course the display elements may be quickly and readily shifted to various relative positions and interchanged on the face of the board so as to dispose the elements either in a straight line or partially irregular formation as shown in Fig.1, or in any other suitable arrangement relative to each other. The ground sheet 2| may or may not be used, and it may also be readily interchanged with other different back-grounds to produce different displays.

Referring more particularly to the sheet 2| and Fig. 1, 35 is a representation of trees or hedges imprinted on the face of sheet 2| which may be of suitable green color for providing an appropriate back-ground for the display element 36 which represents a house and which, for example, might be interchanged with another magnetic display element representing, for instance,

an apartment building. It will be understood that the element 35 also designates any selected representation of any other thing or object in any colors or otherwise of any desired objects such as a bird, ship, or the like.

It will also be understood that the sheet 2| may consist of ferrous material and have etched or engraved thereon appropriate and desirable displays and that in case the sheet 2| is formed of paper the display elements or indicia will be attracted to the board 20 therethrough and in instances where the sheet 2| is formed. of iron or the like thatthe latter will maintain the indicia also in a selected position, and in either case an interchangeable back-ground is provided appropriate for the particular matter displayed by the indicia.

In Fig. 'l the center line X-X indicates the longitudinal axis of the magnet and its magnetic field which it will be observed illustrates the proper mounting of the magnet 24 relatively to such indicium 34 to thereby secure the following advantages:

((1) The maximum force of attraction is as practically possible at the balance point relatively to the center of gravity of the indicium; and

(b) The longitudinal axis of the magnetic field is, as practically possible parallel or nearly parallel, to the longitudinal center line of the indicium (or, in other indicia, to that portion of the section of the indicium in which the magnet is mounted).

In Fig. 3 the magnets 24 are shown, as far as practically possible, at substantially balanced points relatively to the center of gravity of such indicium 23, and the magnets are so mounted that their adjacent poles indicated by N and S are of opposite polarity. This mounting is preferable to'that where adjacent poles of adjacent magnets are of like polarity.

In Figs. 11 to 17 inclusive I show, for purposes of illustrating the preferred embodiments of my invention, the letters N, W and 0.

Among the features of my invention are the thin display face 4|) and side walls 40 which define the hollow indicia and the struts 4| which are formed integrally with the display face wall 40* and a pair of spaced side walls 4|) and which struts or cross-walls 4| extend transversely, and preferably at a right-angle, to the spaced side walls 4|) and at the ends of the cavities 42 for the magnets 43. reenforcing cross-walls 4| defining the ends of the magnet cavity 42 is only slightly longer than the magnet 43 and the portions of the side walls 40 defining the magnet cavity 42 are each provided on their inner faces, and preferably near the transverse reenforcing walls 4|, with a pair of integral spaced small ribs 44 preferably disposed transversely .to the plane of the display face 40 The distance between a pair of such small oppositely disposed ribs 44 is slightly less than the width of the magnet. The thickness of the display face wall 4|! is about 4, of an inch and that of the side walls 40 is about of an inch.

- The thickness of the struts 4| is preferably about of an inch and cross walls 45 formed with a small hole 46 adapted to receive therein a pin 41 may also be provided to thereby adapt the use of such display elements as a pin element for support on a back-ground of wood or paper in which case the magnets of course are not employed in such element. The display elements so made of a light-weight thermoplastic material of such thin walls weigh comparatively very little, can be manufactured at comparatively low cost and may be easily retained by the magnets against displacement.

The letters N and W shown in Figs. 11 and 12 are provided with separate walls 45 for the pins 41 but these pin-retaining walls 45 may be combined with certain of the reenforcing struts 4| as indicated by numeral 46 in the letter 0 shown in Figs. 11 and 12.

My improved and preferred method of making magnetic-display elements from light-weight thermoplastic material, such as Bakelite or tenite consists in molding or otherwise forming the display element, then heating a. metallic element adapted to be magnetized to a suflicient' temperature, about 300 F. for tenite or'to about the melting point of the display element material, and then forcibly inserting such heated metallic element between the opposing ribs 44 until the pole ends of such metallic element are substantially flush with the back or rear face of the display element, then abrasively surfacing thedisplay element and pole ends ofthe metallic element so that same lie in substantially a true plane and then magnetizing the metallic element with opposite pole characteristics.

Heating the metallic element will cause a slight softening of the outer portions of the ribs 44 which contact with the metallic element to there- The distance between the.

by more securely frictionally retain such metallic element against displacement.

Due to the fact that the magnets 43 are small in size ranging in lengths from to of an inch for display sign letters and numerals up to two inches in height I have found that the above method has advantages over a method wherein already magnetized magnets are inserted in the display element and thereafter attempted to be plane-aligned or surfaced. By my method of surfacing the unmagnetized metallic element, the filings do not stick to the metallic element as they would if it was magnetized, and furthermore, the handling of the larger complete display element with the metallic elements therein facilitates the magnetizing operation of the magnets as compared to the manual and individual handling of such small metallic elements. I have also found, as above pointed out, that the surfacing operation of the display element with the unmagnetized magnet elements can be done more economically either by individual manual surfacing or group surfacing or by a traveling belt conveyor having slotted receptacles thereon in which groups of such display elements are carried past a rotary abrasive surfacing element.

Due to the small cross-section of the rounded retaining ribs 44 the unmagnetized magnet element may be forcibly inserted into place between such sets of ribs 44 under normal temperature without preheating, for frictional retainment therebetween, whereupon the rear face of the element and the unmagnetized element may be surfaced and plane-aligned and finally the metallic element may be magnetized.

In both of the above methods of hot and cold magnet insertion, it may be pointed out that the rear face of each of the display elements is thoroughly brushed after the abrasive surfacing operation to remove all loose particles before magnetization of the magnet element.

The above methods may be applied to the making of the indicia illustrated in Figs. 1 to inclusive.

Preferably a light-weight, non-magnetic thermoplastic material such as Bakelite or tenite, or plastic wood may be used for the indicia and the walls are of a minimum thickness, about a: of an inch, whereby a comparatively small magnet may be employed, the latter preferably being made of cobalt steel material which provides an eflicient permanent magnet although because of its small size is comparatively expensive, as in the practice of the invention very small bars thereof may be used for providing the magnet, such bars being so small that they are not susceptible of bein drilled for attachment to the indicia with rivets or the like. 1

Throughout the specifications and claims the word indicium is broadly understood to include any indicia or concrete representation of an yisible object or thing such as, for example, a

letter, numeral, pictorial illustration, trade-mark or symbol. The indicia being preferably formed of a hardened plastic or semi-plastic material.

I do not wish to be restricted to the size, form and proportions of the various parts, and obboard of para-m netic material which consists in the steps of molding or otherwise forming the indicium with a recess in its rear face, then inserting a metallic element in the recess of the rear face thereof, then surfacing the rear face of the indicium to produce a plane-aligned face, and

, then magnetizing the metallic element.

2. The method of making a thermoplastic display indicium provided with a magnet adapting the indicium to be magnetically supported on a board of para-magnetic material which consists in the steps of molding or otherwise forming the indicium with a recess in its rear face, then heating a metallic element and while so heated inserting such metallic element between opposed wall portions of said recess within the rear face of the indicium, then surfacing the rear face of the indicium and said element, and then magnetizing the metallic element so that its opposit? ends have opposite magnetic pole characterist cs.

3. The method of making a thermoplastic display indicium of very thin-walled shell-like structure having a pair of spaced ribs formed integrally with spaced wall portions thereof and provided with a magnet held between said ribs adapting the indicium to be magnetically supported on a board of para-magnetic material viously changes could be made in the constructlon herein described without departing from the spirit of the invention, it being only necessary that such changes fall within the scope of the appended claims.

I claim: 1. The method of making a thermoplastic diswhich consists in the steps of molding or otherwise forming the indicium with a recess and a pair of spaced ribs extending transversely to the side walls of the indicium, then heating a metallic element to substantially the melting point of the thermoplastic material and while heated inserting said metallic element within the recess in the rear face of the indicium between said ribs to thereby cause a softening of said ribs and frictional retainment of said metallic element between said ribs, then abrasively surfacing the metallic element into plane-alignment withrthe rear face of the indicium, then brushing the loose particles from the indicium, and then magnetizing the metallic element.

4. A display device formed of non-magnetic thermoplastic material comprising a thin-walled hollow structure including a display surface wall formed integrally with side walls defining the structure, said side walls having rear planealigned portions adapted to bear against a display board of para-magnetic material, a pair of spaced intermediate walls disposed transversely to said side walls defining a magnet cavity, and a bar magnet in said cavity with magnetic portions thereof approximately flush with said side wall plane-aligned portions, and means for securely retaining the magnet in said cavity.

5. A display device formed of non-magnetic thermoplastic material comprising a thin-walled hollow structure including a display surface wall formed integrally with said side walls defining the structure. said side walls having rear planealigned portions adapted to bear against a display board of para-magnetic material, a pair of spaced intermediate walls disposed transversely to said side walls defining a magnet cavity, porbear against a display board of para-magnetic material, said display device having an open cavity defined by the side walls and a pair of spaced opposed ribs between the side walls of the device,

and a bar magnet frictionally held in said cavity between opposed ribs of the side walls and with a face of. said magnet approximately flushwith the abutting edges of the side walls, said magnet having the sides thereof slightly spaced from the adjacent inner faces of the side walls of the cavity of the display device. 7

7. The combination of a display board of paramagnetic material, a shell-like hollow display device on the face of said board of non-magnetic material having a display surface and side walls adapted to bear against the face of the board, said display device having an elongated cavity in the rear face thereof extending throughout the entire body of the display device, a bar magnet secured in said cavity with a face thereof ap- 7 structure, said side walls having rear planeproximately flush with the rear edges of said aligned portions adapted to bear against adisplay board of para-magnetic material, a pair of spaced intermediate walls of substantially greater thickness than the side walls of the structure disposed transversely to said side walls, and a bar magnet frictionally held between the side walls of the device with magnetic portions thereof approximately flush with said side wall planealigned portions.

9. A shell-like display device of non-magnetic material comprising a wall constituting a display surface, continuous side walls formed integrally with said display surface wall, said side walls and display surface wall being of comparatively thin section and defining a hollow chamber open on the rear face of the device and the rear edges of said side walls being disposed in plane- -a.lignment adapted for mounting on a display board, and a transverse wall of comparatively greater thickness than said side walls formed inte'grally with spaced side wall portions, said display device being adapted for mounting upon a paramagnetic display board by the insertion of one or more magnets within said hollow chamber for frictional retaimnent between spaced portions of said side walls.

- JOHN H. SCHARF. 

